Airfoil tip construction



Aug-28,1945. WATTER Em 383,635

AIRFOIL TIP CONSTRUCTION A Filed March 6, 1943v 4 Sheets-Sheet 1 INVENTORS. Michael Wetter CrorgeW. Pc'mcoleVA 87 i fm ATTORNEY Aug. 28, 1945'.

M. wA'rTER ETAL 2,383,635

AIRFOIL TIP CONSTRUCTIN Filed March 6, 1943 4 Sheets-Sheet 2 Mrz www ma@ VWP Ndw uw. MG.

BY frLf/W AATTORNEY M. WATTER Eer Al. 2,383,635

AIRFOIL TIP CONSTRUCTION Filed' March 6, 1945 4 Sheets-Sheet 4 1 N VEN TORS Michael Wat ter ATTORNEY CreorgeW Pcmcoe Patented Aug. 28, 1945 l 2,383,335 AmFolL TIP CONSTRUCTION Michael Watter and George W. Pancoe, Philadelphia,vPa., assignors to Edward G. Budd Manufacturing Company, Philadelphia, Pa., a corporation of Pennsylvania Application March 6, 1943, Serial'No. 478,234

v 10 Claims. (Cl. 244-123) This invention relates to an airfoil structure and particularly to a tip structure adapted to form the tip of a` Wing, fin, stabilizer or other form of airfoil or similar structure.

An object of this invention is to provide a tip structure for airfoils or the like having an improved arrangement of strainA resisting members so constructed as to provide maximum stress resistance with relativelylight weight; which can, if desired, be formed entirely of material such as stainless steel; and which forms in eiect a structural unit with the associated airfoil or similar structure.

These and other objects which will be apparent are attained by the present invention, one embodiment of which is shown for the purposes of illustration in the accompanying drawings, in which:

Fig. 1 is a view in side elevation of an airfoil tip constructed in accordance with one embodiment of this invention, showing the same employed to form the upper tip of a vertical stabilizer iin having an associated rudder mounted thereon; .l

Fig. 2 is` an enlarged view of the tip structure shown in Fig. 1;

Fig. 3 is a vbottom plan` view, front the line 3 3 of the structure shown in Fig.,2;

Fig. 4 is an enlarged vertical section taken on the line 4 4 of Fig. 2;

Fig. 5 is a side elevation on the same enlarged scale as Fig. 4 of a portion of the tip shown in the broken-line area 5 of Fig."2;

Figs. 6 and 7 are enlarged partial sectional views onthe lines 6 6 aand 1 1, respectively, of Fig. 2;

Fig. 8 is an elevation on an enlarged scale of the structure embraced within the 'broken-line area 8 of Fig. 1 showing the connection at one point between the tip and the main airfoil;

Fig. 9 is a vertical section on the line 9 9 of Fig. 8; v

Figs. 10 and 11 are sections on the lines III-l0 and Il l l, respectively, of Fig. l9;

Fig. 12 is an enlarged elevation of a detail, showing one type of a connection between the tip structure and the main airfoil body; I

Fig. 13 is a section on the line l3 l3 of Fig. 12;

Fig. 14 is an enlarged elevation of the joint comprised Within the broken circle I4 on Fig. 2;

Figs. 15, 16 and 17 are sections on the lines l5-l5, l6 l6, Il ll, respectively, of Fig. 14;

Fig. 18 is a section on the line l8 l8 of Fig. 17;

.Fig 19 is a bottom plan view from the line lil-l 9 of part of the structure shown in Fig. 17;

Fig.- 20 is an enlarged side elevation of the joint comprised in the area of the broken circle 20 in Fig. 2;

' `g. 21. is a section on the line 2| 2-I kof Fig. 20:

Fig. 22 is a section on the line 22 22r of Fig. 20; I

n Fig. 23 is an enlarged sec on on the line 23-23 of Fig. 2; and,

Fi'g. 24 is a section on the line 24 24 of Fig.

In the present invention a structure, such as an airfoil, is provided with a tip structure which is secured thereto in such a lWay as to form an integral part of the airfoil structure. The tip structure embodies a cantilever truss and is mounted on vthe airfoil so as to project outwardly and to provide a cantilever support over-reaching one edge of .the airfoil structure to form a support for such a device as, for example, the upper bearing 'of an associated rudder shaft. The cantilever truss system of the tip `structure is so related to the airfoil Ibody that the main elements of the cantilever truss system are integrally united with the main stress resisting members of the associated airfoil structure, and the joints between the two are constructed and arranged to provide a rugged connection of relatively light weight.

As iuustrated in Fig. 1, the invention is shown portion of the tip to be described herein, and

near its ends. The tip truss structure also includes forward and rearward end'ri'bs 46 and 41, re-

intermediately to hinge connections 3l and 38.

The tip structure 4I, Figs; 2 and 3, includes a base frame or rbulkhead42, which extends alongA substantially the entire bottom side thereof located adjacent to the airfoil on which it is mounted and which constitutes the base member of a cantilever truss structure. The truss structure also includes a king-post rib' 43 and a pair of diagonal truss means 44 and 45, extending forwardly and rearwardly, respectively, from the upper end of the king-post 43 and connected to the bulkhead 42 spectively, and -a plurality Vof vertically extending intemedi-ate rilbs 50, all parallel to the king-post rib 3. 1

'I'he' center or icing-postv Vrib 43 (see Figs. 3

bers 48 are welded, respectively, to stiifening plates the inner edges of which are offset to overlap as indicated at 53 in Fig. 6. The two plates 5| are joined by la tie-plate 54 welded to them adjacent their lapped edges.

As shown in Figs. 3 and 4, each diagonal truss means 44 or 45 comprises a pair of parallel ch'annel-shaped members 44a and 44h or 45a and 46h, respectively. The diagonal members 44a and 45a adjacent one surface are welded at their upper ends, Figs. 6, 20 and 21, to brackets 51- which are welded to a gusset plate 58 which is in turn welded to the upper end of the king-post rib chord member 46.Y Likewise, the diagonal members 44h and 45hare welded to similar brackets 51 which are welded to a gusset plate 58 which in turn is welded to the other king-post rib chord member 48.

'Referring to Figs. 23 and 24, each of the forwar'clly extending diagonal members 44a, 44h is '.connected to the bulkhead 42 and to the lower ends ofthe spaced ch'ords of the forwafd rib 46 by gusset plates 6|, the gusset plates each having a horizontal flange 62 welded to the bulkhead 42 and a vertical flange 63 welded to a chord member 66 of the front end rib 46. Therib chord members 66 project downwardly through the bulkhead 42 adjacent a,transverse stiffening member 6.5 which is secured across the bottom face of the bulkhead 42. The forward end rib 46 is generally representative of the other vertically extending intermediate ribs 50 and the rear end rib 41. Figs. 4 and 5 illustrate another such rib, the same comprising a pair of Z-shaped chord members 66. In Fig. '7 the rear end rib 41 is shown.

Where the conformation of the tip structure is such th'at the marginal edge or tip bow 69 is relatively blunt, as in Fig. 4, the spaced upper ends of the rib chord members 66 are welded to a marginally flanged transverse nose plate 1| which is in turn welded through its flange to the tip bow 69. The rib chord members 66 are intermediately connected by a transverse channel member 13 or the like and at their lower ends extend through the web of the bulkhead 42. The projecting ends of the chord members 66 are attached through the medium of gusset plates to the ends of channel-shaped stiffeners 65 which are welded to the outer face of and form a part of the bulkhead 42.

Fig. 6 shows a construction similar to that of Fig. 4, but of the king-post rib 43, and here the transverse nose plate 1| is welded through its marginal flange to the tip bow 69 and to the rib members 48 and 54. y

Where th'e tip bow 69 is relatively sharp in section, as in Fig. '7, the rib chord members 66 overlap and are welded together and to an extension 11 of the transverse nose plate 1| which is in turn welded through its marginal fiange'to the tip bow 69.

The tip bow 69 intermediate adjacent ribs and intermediate the end ribs and the bulkhead 42 is closed in by rigidifying plates 12 having marginal side flanges 12a welded to the tip bow 69 and end flanges 12b welded to the adjacent nose plates 1|.

welded thereto, is secured to the ribs by channelshaped clips 84 welded to the sides of the stiieners 83 and to th'e rib chord members 66.

Referring to Figs. 14, 15, 16 and 17, the lower ends of the rearwardly extending diagonal members 45a and 45h forming the rear' diagonal truss mem-ber 45, are each connected to an angularly bent gusset plate 85 which includes the backing plate 85a welded thereto, the gusset plates at the bottom of the structure being connected by two transverse U-shaped brackets 86 and 81 having flanges 88 at each' end welded to the plates 85a of the opposite gusset plates 85. As shown in Fig. 15, the iower ends of these rib chords 66 are connected above the bulkhead 42 by a transverse strut member 14. The two rear ribs do not extend through the bulkhead lest they interfere with' the action of the rudder.

Referring to Figs. 17, 18 and, 19, the bottom webs of the U-shaped brackets 86, 81 are welded to the bulkhead 42, and a bearing supporting ring 9| is bolted to the lower face of the bulkhead by bolts 92 extending through the bulkhead and the U-sh'aped brackets. Roller bearing 83 is mounted in the bearing ring 9| to rotatably support the upper end of the rudder shaft 35.

Again referring to Fig. 1, the tip structure above described is adapted to form the tip of an airfoil such, for example, as the fin 3| on which it is mounted by ,connecting the king-post rib 43 of the tip structure to the main spar 33 of th'e fin, and by connecting the forward end rib 46 of the tip to the forward spar 32 of the fin.

As shown in Figs. 8 to 11, the main spar 33 of the fin structure is formed by chord members |0I, only one of which is shown, which extend upwardly along the sides of the fin structure and which are connected by suitable transverse strut members. The upper transverse strut member |02 is channel-shaped, has a ridged reinforced web |03 and is welded to one wall of each chord |0| through an intervening Z-shaped gusset plate |04 extending upwardly above the edge of the iin structure where it is welded to the downwardly projecting end |05 of one of the chord members 48 of the king-post rib 43 of the cantilever tip structure.

` A flanged transverse channel member |06 has one wing abutting and welded to the top wing of the transverse n truss member |02, and the web thereof Welded to th'e Z-shaped gusset plate |04,

while its other wing is welded to the outermost wing of the transverse stiiening member 65 of the bulkhead 42. The nn structure is provided on each side at the top with a Z-shaped strengthening member |08 extending along th'e arfoil surface and transversely of the Spar 33. The member |08 at each end r(Figs. 9 and 11) is connected to a Z-shaped connecting plate |04 and also to one wing of the fin spar chord |0| by a bent bracket |09. An angularly bent chord member of the tip bulkhead 42 has one flange Welded to the lower edge of the blanket skin 82.

Referring to Figs. 1, 12 and 13, the forward anchorage of the diagonal truss member 44 of the tip is connected to the upper end of a. forward spar 32 of the iin structure, At .this point, an angle-shaped transverse fin spar strut member ||3 connects the n edge-strengthening members |08 at each side of the body. The rib chord members 66 of'the forward end rib 46 of the tip extend downwardly through the bulkhead 42, as previously noted, and each is connected to a gusset plate 15 which 'is in turn welded to a gusset plate H5 secured to the vertical wing asaacss of the angle member H8. The lower edge of the blanket skin 82 of the tip structure is here welded to the angularly bent chord member as before. The skin H1 for the fin body is welded to the horizontal edge strengthening member |08. A cover finishing strip H9 is employed to close the space between the skins 82 and ||1 of the tip and iin structure.v

'I'here is thus provided an airfoil tip structure which includes a cantilever' truss construction, the main stress points of the base of the cantilever tip truss being immediately associated with the main stress points of the fln, that is, with the ends of the two spaced spars and the rudder shaft of the fin. The tip construction is also easy to fabricate and assemble, the ribs, skin blankets, bow tip, and bulkhead, each comprising one sub-assembly, which sub-assemblies. may be welded together successively until 4nally the bulkhead is applied. Thereafter the entire tip assembly may conveniently be welded through companion projecting elements to the fin body and finally the skin finishing strips H9 applied.

The structure is such that assembly may be effected yby the following procedure:

.The tip bowls made as one sub-assembly, including the pre-shaped double-curved skin cover 69, the nose plates 1| with projecting ends, andthe rlgidifying closure plates 12.

The skin blankets and parti-ribs form two other sub-assemblies or half-shells, including for each half-shell a skin blanket composed of skin 82A and stiieners or stringers 83 secured to rib and the diagonals 44h, 45h form a part of the.

other half-shell assembly. To one of the halfshell assemblies one end of the struts 13 and one side of the splice plate 54 may be secured.

The other sub-assembly comprises the bulkhead sheet 42 having the illustrated lightening and access openings to which are secured the transverse rib struts 65, the marginal chord members lI-i, the interior rib strut 14, and the interior transverse bearing bracket struts 86, 81.'

The tip bow sub-assembly -is placed in a jig along with the' half-shells and by reaching into the interior withl suitable welding tongs the projecting ends of the tip bow nose plates are welded to the ends of the rib chords 66 and 48, and the rib chords such is in Fig. 7 which overlap are welded together. Also the unattached ends of the rib struts 13 are Welded to the rib chords of the opposite half-shell and the other edge of the splice plate 54 is welded to the rib plate 5|.

Either before or after this assembly is made but before the bulkhead is placed the tip bow skin 69 is welded to the half-shell skins 82.

Then this bulkhead 42 is pushed into position and yWelded through the edge chord to the skin sheets 8l.f By reaching through the access openings the struts 14, 86 and 81 are welded to the half-shell assembly. The bearing 8| is then secured by the bolts 92, though this may be done after the tip has been attached to the n.

The4 tip is. attached to the iin by welding through the mating flanges of .the .channels 85 and |06 (Fig. 10) and the parts 15, ||5 (Fig. 13),.

Then the gap cover strips I I9 are bolted in place,

nuts having previously been secured inside the assembly in usual fashion.

Aithough 1 have described in detail-'ene specific embodiment of this invention inconjnjection with a specific type of airfoil structure, it will be ap- 1 parent thatsuch description is for the purposes of illustration only and that the invention can be variously modified and. adapted within the scope of the appended claims.

What is claimed is:

1. An airfoil structure comprising in combination, a stabilizer iin having a longitudinally extending spar, a tip structure for said fin having a bulkhead along the edge thereof adjacent said fin, a central rib forming a kingpost connected to said bulkhead and extending between said bulkhead and the marginal edge of said tip, means connecting said king-post to the longitudinally extending spar of said n, diagonal truss means connecting the outer end of said kingpost with the-bulkhead adjacent the opposite ends, said tip structure extending outwardly to form a cantilever support overhanging the trailing edge of said iin. and a shaft bearing positioned on the overhangingportion of said bulkhead and supported by the adjacent end of one of saiddiagonal truss means.

2. An airfoil structure comprising in combination, a stabilizer fin having spaced longitudinally extending spars, a tip structure for said fin having a. bulkhead along the edge thereof adjacent said fin, a'central rib forming a king-post connected to said bulkhead and extending between said bulkheadand the marginal edge of said tip,

means connecting said king-post to one of the longitudinally extending spars of said fin, front and rear diagonal truss members connecting the outer end of said king-post with the bulkhead adjacent the opposite ends, means connecting a front diagonal truss member at said bulkhead to the other spar of said fin, said tip structure extending outwardly to form a cantilever support overhanging the trailing edge of said n, and a shaft bearing positioned on the'overhanging portion of said bulkhead and anchored to the adjacent end of one of said diagonal trussmembers.

3. An airfoil structure comprising in combination, a stabilizer fin having a longitudinally extending spar, a tip structure for said iin having a bulkhead along the edge adjacent said fin, a central rib in said tip structure forming a kingpost vconnected to said bulkhead and extending between said bulkhead and the marginal 4edge of said tip, means connecting said king-post rib to said longitudinally extending spar comprising .a frame member supported on said spar and extending transversely of said airfoil structure, a second frame-member connected to said central rib and extending transversely of said tip structure and adapted to rest upon and be supported by said first-named frame member, and means for connecting said frame member to said spar.

4. An airfoil structure comprising in combination, a stabilizer fin having a longitudinally eX- tending main spar, a second parallel forwardly located spar, a tip structure for said n having a bulkhead along the edge thereof adjacent said iin, a central rib lforming a king-post connected to said bulkhead and extending between said bulkhead and the marginal edge of said tip, means connecting said king-post rib to said main extending spar, forwardly and. rearwardly extending diagonal truss members connecting the outer end of said king-post with the bulkhead -adjacent the opposite ends, and means for antion; a stabilizer iin having a longitudinally extending main spar, a second 'parallel forwardly located spar, a tip structure for said fin having a.

bulkhead along the edge thereof adjacent said fin, a central rib forming a king-post connected to said bulkhead and extending between said bulkhead and the marginal edge of said tip, means connecting said king-post rib to said main spar, forwardly and rearwardly extending diagonal truss members connecting the outer end of said king-post with the bulkhead adjacent the opposite ends, and means for anchoring the forward end of said forwardly extending truss member to the forward vertical spar of said fin structure,lincluding a rib in said tip structure, a gus. set plate connected to the forward end of said truss member and to said rib and said bulkhead,

and means connecting the projecting end of saidV rib to said forwardly located spar.

6. An airfoil structure comprising in combination, a main body portion, a tip sub-assembly secured to and forming an end extension on the main body, thev body and tip comprising a frame and covering skin, the ti'p overhanging one edge of the main body and having on the overhang a .bearing anchorage for hinging a movable airfoil.

'7. An airfoil structure comprising in combination, a main body portion', a tip sub-assembly secured to and forming an end extension on the main body, the body and tip comprising a frame and covering skin, the tip overhanging one edge of the main body and -having on the overhang a bearing anchorage for hinging a movable airfoil, the main body having a spar adjacent the side of the tip overhang, and the tip having a spar extension secured to the end of the spa'.` and a diagonal brace from the upper part of the spar extension into the overhang near the bearing anchorage.

8. An airfoil structure comprising in combina-- tion, a main body portion, a. tip sub-assembly se cured to and forming an end extension on the main body, the body and tip comprising a frame and covering skin, the tip overhanging one edge of the main body and having on the overhang a bearing anchorage for hinging a movable airfoil;

the main body having a first spar adjacent the side of the tip overhang and a second spar on that side away from the overhang, and the tip 5 having a spar extension secured to the end of the first spar and diagonal braces from the upper part of the spar extension to the region of the bearing anchorage and the region of the end of the second spar.

9. An airfoil structure comprising in combination, an airfoil body having spaced longitudinally extending spars, a tip structuresecured to said body and having a bulkhead along the edge thereof adjacent the body, said tip including an intermediate rib forming a king-post connected to said bulkhead and extending between said bulkhead and the marginal edge of said tip, means connecting said king-post rib to one of said body spars, diagonal truss means connecting the outer end of said king-post with the buikhead adjacent the opposite ends, and means connecting the bulkhead and tip at one end of the truss means on one side of the king-post to another body spar.

10. An airfoil structure comprising in combination, an airfoil body having spaced longitudinally extending spars, a tip structure secured to said body and having a bulkhead along the edge thereof adjacent the body, said tip including an intermediate rib forming a king-post connected to said bulkhead and extending between said bulkhead and the marginal edge of said tip, diagonal truss members connecting the outer end of said king-post with the bulkhead adjacent the opposite ends, and means connecting the tip at one end of one truss member to another spar of said body; said tip projecting outwardly to form a cantilever support overhanging the trailing edge ofl said airfoii v bcly for an airfoil hinge, a m diagonal truss member being connected to the bulkhead at said hinge.

MICHAEL WATTER. GEORGE W. PANCOE. 

